Technical Field
The present application discloses a light-emitting element comprising a semiconductor light-emitting stack and a wavelength conversion device to emit a white light.
Description of the Related Art
Following incandescent light, traditional lighting devices have been gradually substituted by solid-state lighting devices consisted of the light-emitting diodes because the light-emitting diodes (LEDs) have the characteristics of low power consumption, environmental protection purpose, long operational life, and small volume. Moreover, the companies are aggressive to develop the LED capable of emitting a white light.
Among the lighting technologies, a white light-emitting diode (WLED) can be realized by a light source comprising a blue light-emitting chip and a red light-emitting chip with a phosphor to emit a yellow light or a green light and be mixed with the light from the chips to form a white light. Or, a blue light-emitting chip as a light source is companied with a phosphor to emit a yellow light or a green light to be mixed with the light from the blue light-emitting chip to form a white light-emitting diode. There are differences such as cost and color temperature between the two types of constructions, but both the two types have a problem of spreading the phosphor. In order to improve characteristics such as color rendering index, light-emitting efficiency and uniformity of the color, many different methods of spreading the phosphor have been applied to improve the uniformity of the color or the amount of light extraction of the WLED.
Among the methods of spreading phosphors, the method of mixing two different phosphors and spreading the mixture is likely to induce absorption. The absorption issue results from the phosphor which emitting a light of a longer wavelength is more likely to absorb the light of shorter wavelength emitted by another phosphor, which is one of the reasons that the light-emitting efficiency of a white light is lower.
The light-emitting diode comprising above phosphors can be further connected to other components to form a light-emitting apparatus. The light-emitting apparatus comprises one sub-mount having one circuit, one solder on the sub-mount which fixes the light-emitting diode on the sub-mount and forms an electrical connection between the circuit on the sub-mount and the light-emitting diode, and an electrical connection element to electrically connects the electrode of the light-emitting diode and the circuit on the sub-mount, wherein the sub-mount can be a lead frame or a large size mounting substrate for the convenience of designing the circuit of a light-emitting apparatus and improve the effect of heat dissipation.